|Ordered||2 Feb 1935|
|Laid down||4 Mar 1936||F. Krupp Germaniawerft AG, Kiel (werk 551)|
|Launched||31 Jul 1936|
|Commissioned||3 Aug 1936|
|Successes||5 ships sunk, total tonnage 10,706 GRT|
1 auxiliary warship sunk, total tonnage 605 GRT
1 warship damaged, total tonnage 11,500 tons
Stranded on 27 March 1940 south-east of Mandal, in position 58.01N, 07.29E, after running aground off Oldknuppen Island following a navigational error.
Interned in Norway at Kristiansand-Süd. Released to Germany on 9 April 1940.
Stricken 5 Aug 1944 at Pillau. Scrapped in February 1945.
Attacks on this boat and other events
9 Sep 1939
The British submarine HMS Ursula (N 59) (LtCdr G.C. Philipps, RN) fired the first British submarine torpedoes of the war when unsuccessfully attacking U-35 and U-21 with a spread of five torpedoes some 23 miles north of the island of Schiermonnikoog, Netherlands. (Sources: Dr. Jürgen Rohwer)
6 Nov 1939
HMS Sealion (Lt.Cdr. B. Bryant, RN) fired 6 torpedoes at U-21. They all missed their target.
2 recorded attacks on this boat.
Men lost from U-boats
Unlike many other U-boats, which during their service lost men due to accidents and various other causes, U-21 did not suffer any casualties (we know of) until the time of her loss.
There was another U-21 in World War One
That boat was launched from its shipyard on 8 Feb 1913 and commissioned into the Imperial Navy on 22 Oct 1913. The Naval war in WWI was brought to an end with the Armistice signed on 11 Nov, 1918. Read about SM U 21 during WWI.